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schematic

simulate this circuit – Schematic created using CircuitLab

Ip(bias)=200nA rd=differential resistance=5Mohm a=infinite What should be its output? I am confused if I should consider negative feedback and consider bias current gives only input offset voltage of straightway say that OPAMP is saturated.

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  • \$\begingroup\$ Assume Vin- = Vin+ =0 (ignore Ip*100=20uV) and Vout drives Vin to that voltage, so what is Vout ... Note R's are equal \$\endgroup\$ – Sunnyskyguy EE75 Mar 2 at 6:52
  • \$\begingroup\$ How can I ignore 1V (200nA*5M=1V) \$\endgroup\$ – Buzz bee Mar 2 at 7:16
  • \$\begingroup\$ So in a nutshell, in ideal case when input bias current \$I_b = 0\$ and also input impedance \$Z_{in} = \infty\$, you understand that the \$V_{out} = V_{in} = -1V\$. What do you want to ask that how to derive the value of \$V_{out}\$ if \$I_b \ne 0\$ and \$Z_{in} \ne \infty\$ right? \$\endgroup\$ – Unknown123 Mar 2 at 10:59
  • \$\begingroup\$ @Unknown123 right \$\endgroup\$ – Buzz bee Mar 2 at 11:19
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    \$\begingroup\$ You add additional voltage sources to the schematic, with the new voltages being the error voltages. You may need to perform Norton to Thevenin conversions. \$\endgroup\$ – analogsystemsrf Mar 2 at 13:36

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